CD68 and pulmonary fibrosis: Notwithstanding correlations do not imply direct cause-effect relationships, we think that the significant negative correlations observed in this group of patients with IPF between CD8+TLs and functional indices and the positive correlation observed between the same cells and clinical indices estimating the disease severity as well as the correlation between CD68+ cells with FVC and FEV1 might suggest a potential pathophysiologic relevance for mononuclear cells and especially CD8+TLs in the pathogenesis of pulmonary fibrosis.